With the rapid increase in the use of digital videos, vigorous efforts are being made to develop more efficient techniques to extract material information from video data. Recently, the technique to extract a foreground layer of an image having a background and a foreground is being actively researched. The process of partitioning a digital image into multiple layers (e.g., a foreground and a background layer) is referred to as image segmentation, and the technique of extracting a foreground of an image is referred to as foreground segmentation. An example application of foreground segmentation is high quality live background substitution in a visual communication scenario, e.g., teleconferencing or instant messaging.
One of the high quality and real-time foreground layer extraction approaches may be known as so-called “background cut.” One characteristic component of background cut approach is “background contrast attenuation” which may reduce foreground segmentation errors caused by high contrast edges in the clutter background. Background contrast attenuation may be based on the consideration that contrast from the background may be dissimilar to the contrast caused by the foreground/background boundary. Based on the above consideration, background cut obtains a background contrast map from an initial background image and attenuates the contrast corresponding to the background layer in a foreground-containing image by using the background contrast map, thereby making it relatively easier to extract a high quality foreground layer.
Background cut, however, may have some limitations. For example, background cut could improve upon the conventional techniques for images taken by a stationary camera with a known and still background. This is because the background cut may require an initial, stationary background image to attenuate the contrast in the background and accurately extract a foreground layer from the image. That is, the background cut may not be applied to video images where the background keeps changing (i.e., the camera is not stationery).